I usually have a pot of Basil on my windowsill, but the current one had got very manky and shriveled-looking, so I put it in my compost crock and replaced it with another from the supermarket. Anyway, I opened my crock later in the day and found three, green caterpillars, clinging to the old Basil! I have picked them out and put them on my new Basil plant, where they are happily munching away (and dropping their poo all over the windowsill!). I will now have to buy another Basil plant for my own use (DH thinks I’m crazy!). Anyway, I’m wondering what kind of caterpillars these are, any ideas? I think the old Basil plant came from Tescos, so presumably the caterpillars came with it, maybe in egg-form??? Being a bit of a bug-avid (ignoring my previous post about ants!), I’m keen to know what these caterpillars will turn into and am wondering if I should put my pot of Basil into some kind of aquarium to keep the caterpillar’s contained if they try to wander off to make a chrysalis (we’re moving house soon, so the moving may disturb them). What with the ants and the caterpillars, my kitchen is looking more and more like a wildlife documentary by the minute!!

Be wary of putting insects (or caterpillars) on supermarket or garden centre bought potted plants, because often the soil is infused with pesticides, which will kill the insects when they eat the leaves.

Oh, if they are small, you can put them in a cheap tupperware (see through is best, and tall/high rather than long and shallow) with cut stems of their desired plant (basil, lol). I have tiger moth caterpillars and red admiral caterpillars, and the advice was to give them dry leaves because wet leaves can make them ill. That was the same advice as for the 3 privet hawkmoths (which have now pupated).

You may be best getting a butterfly habitat (like these http://www.insectlore-europe.com/butgar5cat.html) if you want to see them through to chrysalissing & emerging. I have the very large butterfly tent/bungalow for when my 10 red admirals and 5 painted ladies are ready to hatch out (in about a week or so they ‘should’ chrysalis, and about 2 weeks later emerge as butterflies).
Not sure about the tiger moths (of which I bought 10 but they are/were so tiny I counted at least 13, lol!) I think they are meant to grow slower and dont chrysalis til next June.

I would contact Dorothy though as she is very very good at identifying caterpillars and best advising how to care for them.

Thanks Pheonix, those are really interesting websites! These caterpillars must have come on the supermarket basil, maybe at eggs on the leaves or something and they’re already yomping into the new pot I bought! I don’t really know whether to put the pot outside or not, or whether to keep them indoors. I don’t want the caterpillar to hatch in the middle of winter as it would die outside. If it’s kept indoors, will it’s cycle be disrupted and it’s timing of when to pupate be put out of sync?? Will shop-bought basil survive if I put it outside now?

It really depends on their cycle and whether they are british caterpillars or not.

Some catapillars take a long time (9 to 12 months) to grow, and the same to pupate. My British Privet Hawkmoth caterpillars pupated a week or two ago. they need to go outside (in an unheated shed or garage) until next May/June, because they emerge in June. If they are kept indoors in a heated home they will emerge too soon to survive outside (as early as Jan or feb).

However, the Red Admiral butterfly caterpillars only hatched a month or two ago, eat loads, are already about 4 times the size they were when I got them (they are now about 1.5 to 2cm long and quite round). They only remain a chrysalis for two weeks so it’s fine to keep them in the house because the temperature is similar to outside anyway… or at least, similar to outside if it was a warm summer.
The painted lady caterpillars also only take a few weeks to grow and chrysalis, and another 2 weeks to emerge as butterflies. They are not Brtish though, they are African and migrate here (and usually go back I believe). So again, keeping them indoors where it is warm is ok too.

I’d e mail Dorothy and see if she can give you any help though because I had a look through our insect book and havent yet been able to identify a basil leaf eating caterpillar, lol.

We had some on our basil a few years ago. I reckon they’d been laid on there when the kitchen window was open, unfortunately I can’t remember what type they were, I think they were something relatively common though.